1. Field of the Invention
The present invention relates generally to the manufacturing and testing of electronic components. Specifically, the present invention relates to a method and apparatus for evaluating the electrical characteristics of each contact pin of an electronic component having multiple contact pins used in the testing of electronic devices, such as integrated circuit devices.
2. State of the Art
Generally, electronic components can be thought of as comprising a case for housing internal circuitry and a connecting structure for establishing electrical communication with the outside worldxe2x80x94external devices such as power sources, test instruments, a second electronic component, or any other electronic device. A common connecting structure used to achieve electrical communication between an electronic component and external devices is a contact pin. A contact pin is a metal, rod-shaped body having an external portion extending from a surface of the component case and an internal portion within the component case. Electrical connecting structures comprising, contact pins are well known in the art.
The external portion of the contact pin body provides a connecting point for establishing electrical contact between the contact pin and an external device. Connection to the contact pin may be temporaryxe2x80x94for example, by using a male-female socket connectorxe2x80x94or connection to the contact pin may be permanentxe2x80x94such as may be achieved using solder. The internal portion of the contact pin body may establish electrical communication with internal circuitry of the electronic component. Alternatively, the internal portion may extend through the component case and project from another surface of the electronic component, thereby establishing a second connecting point on the contact pin. The second connecting point allows an external device electrically connected to the first connecting point of the contact pin to electrically communicate with another external device connected to the second connecting point. One type of electronic component that may have such a structure is what will be referred to herein as a testsite module. A testsite module is essentially a test bed for a second electronic component. The testsite module serves as a conduit between the second component and other external devices, such as a test instrument. Also, a contact pin may provide both a connection to internal circuitry and a second connecting point.
Although an electronic component may have only one contact pin, a plurality of contact pins is routinely necessary. For example, an electronic component may be used in an application that requires multi-channel communication capabilities, thus requiring that the electronic component have multiple contact pins. For an electronic component having multiple contact pins, the contact pins are usually arranged in one or more two-dimensional arrays on the surface of the component case, thereby forming a pin-out. The use of hundreds of contact pins on electronic components is known.
During the manufacture of electronic components, the components are routinely subjected to one or more tests to determine their electrical characteristics. Methods and apparatus for performing electrical characterization of electronic components are well known in the art. The type of electrical testing performed on an electronic component varies widely, depending on the type of component being tested and individual needs. During testing of electronic components having multiple contact pins, electrical communication between the electronic component and test instrumentation is generally established via the contact pins. Thus, of critical importance in the design, manufacture, and testing of electronic components having a plurality of contact pins is the electrical integrity of the pin-out itself.
A damaged or defective pin-out on an electronic component may prohibit communication with the electronic component during testing, or may result in the electronic component producing a false reading such as, for example, a false pass or fail condition. Thus, the internal circuitry of the electronic component may be inaccurately characterized. If the electronic component is a testsite module functioning as an electrical interface between a test instrument and a second electronic component, a damaged or defective pin-out may result in inaccurate characterization of the second component. Characteristics that may be indicative of a damaged or defective pin-out include: a shorted condition between an individual contact pin and any other contact pin in the pin-out (pin-to-pin shorting), a shorted condition between an individual contact pin and the component case (pin-to-case shorting), individual contact pin resistance that exceeds a known threshold (pin resistance), and the existence of a high-resistance connection between adjacent contact pins (pin-to-pin leakage).
Evaluation of pin-out integrity on electronic components such as testsite modules is conventionally performed manually by a test operator using a hand-held multi-meter. The conventional process requires the test operator to measure the electrical characteristics of each contact pin, one contact pin at a time. Electronic components in the form of testsite modules commonly have pin-outs comprised of 54 or more contact pins. When measuring pin-to-pin shorting, for example, the contact pin being evaluated will be checked for a shorted condition relative to every other contact pin in the pin-out and, typically, every contact pin in the pin-out will be evaluated for pin-to-pin shorting. Thus, manual testing can be time consuming and susceptible to human-introduced errors such as, for example, inaccurate measurement, non-repeatability from one contact pin evaluation to the next, and non-repeatability from one electronic component evaluation to the next.
Therefore, a need exists for a method and apparatus for testing the electrical integrity of each contact pin on an electronic component having multiple contact pins. Further, a need exists for a method and apparatus for characterizing the electrical properties of a pin-out that is accurate and repeatable. Additionally, a need exists for a method and apparatus for characterizing contact pins that are adaptable to automation and require minimal intervention by a test operator.
The apparatus of the present invention is generally comprised of a test device, a measuring instrument, and a system controller. The test device is configured to hold an electronic component under test (ECUT) and to establish electrical contact with a pin-out on the component. Simultaneous electrical contact may be established between all contact pins of the pin-out and a contact plate on the test device. If the ECUT has contact pins extending through its case to form a second connecting point on each contact pin, simultaneous electrical contact may be established with both connecting points on each contact pin using a second contact plate on the test device.
The measuring instrument is electrically connected to the contact plates such that electrical communication is established between the measuring instrument and each contact pin on the ECUT. The measuring instrument is also in electrical communication with the system controller, allowing the system controller to direct the function of the measuring instrument. The measuring instrument is configured to measure the electrical characteristics of each contact pin on the ECUT that are indicative of a damaged or defective contact pin. In addition, the measuring instrument may be configured to record and store the measured properties. Electrical characteristics indicative of a damaged or defective contact pin include, but are not limited to, pin-to-pin shorting, pin-to-case shorting, pin resistance, and pin-to-pin leakage.
The system controller is configured to direct the test device and measuring instrument to perform at least a portion of a test sequence on the pin-out of the ECUT. In one embodiment, the contact plates of the test device are each associated with a positioning system adapted for computer control, thereby enabling the system controller to direct the test apparatus to establish electrical communication with the ECUT. The system controller may further be adapted to store and report the results of the test sequence.
The test sequence or method of the present invention may, by way of example only, include the following steps: test operator places an ECUT into the test device; system controller directs the test device to establish electrical contact with the contact pins of the ECUT; system controller directs the measuring instrument to measure at least one electrical characteristic of each contact pin on the ECUT; system controller directs the test device to establish electrical contact with the second connecting point, if any, on each contact pin of the ECUT; system controller directs the measuring instrument to measure another electrical characteristic of each contact pin on the ECUT; system controller directs the test device to terminate electrical contact with the ECUT; system controller directs the measuring instrument to report the test results to the test operator; and test operator removes the ECUT from the test device. This method may then be repeated for another ECUT.